Pot and pan washing machines, of the type used in restaurants, institutions and other eating facilities often involve a large wash tank or basin in which water is circulated about the pots and pans to provide a washing action. One such machine is described in U.S. Pat. No. 4,773,436 issued to Cantrell et al., the specification of which is incorporated herein by reference. The machine of Cantrell includes a wash tank with multiple jets evenly spaced apart at an elevated position along the rear wall of the wash tank. The tank is filled with water to a level above the position of the jets. Pots and pans are placed in the wash tank, and a pump is activated to draw water from within the wash tank and direct it through the jets to create a jet stream. Each jet directs its jet stream toward the bottom wall of the wash tank, the bottom wall then deflects the jet stream upward and towards the front wall of the tank. The front wall then deflects the upward moving jet stream towards the rear wall of the tank, and the rear wall deflects the jet stream downward and back towards the front wall along the bottom wall. The combination of deflections of the jet stream from the bottom, front and rear walls provides a rolling washing action within the wash tank.
The basic components of the wash tank of the pot and pan washing machine of the prior art are shown in FIG. 1. Wash tank 10 includes end walls 12 and 14, rear side wall 16, front side wall 18 and bottom wall 19. A pump can be attached to either end wall; in the embodiment shown in FIG. 1, pump 50 is attached to right end wall 14. An impeller located within pump 50 is driven by electric motor 56. The impeller draws fluid into pump inlet 52 through an intake port (not shown) located in end wall 14. The fluid is then discharged from the pump through pump outlet 54 and into outlet manifold 60. Outlet manifold 60 includes a ninety degree turn, and several other turns, to direct the fluid across the back side of rear wall 16 and out jet nozzles 20 which are protruding through and extending from rear wall 16. The intake port associated with pump inlet 52 is covered by perforated intake manifold 30. Intake manifold 30 includes handle 36 and is removably supported within wash tank 10 for easy cleaning. Intake manifold 30 fits tightly between outer runner 32 and inner runner 34, each of which extends vertically from bottom wall 19. Heating element 40 is positioned between intake manifold 30 and end wall 14 for its protection and to maximize the use of space.
Although the prior art pot and pan washing machine disclosed in U.S. Pat. No. 4,773,436 provides an exceptional wash action, many of the components discussed above hinder the overall efficiency and performance of the machine. The inventions disclosed in co-pending U.S. application Ser. No. 09/947,484 provide components that greatly increase the overall efficiency and performance of the machine, including an improved intake manifold positioned along the rear wall of the machine as shown in FIG. 2. The invention disclosed in U.S. application Ser. No. 09/947,484 provides a scaleable, self-cleaning intake manifold that has a generally linear intake path. Nevertheless, the improved intake manifold itself has several disadvantages that result in a reduction of efficiency and performance.
The main problem with the prior art pump intakes in a pot washing system is that a fluid will take the path of least resistance to the inlet of the pump. Therefore, the volume of fluid nearest the pump intake will be pulled in at a much greater rate than the volume farthest away from the intake. This “sucking” action creates problems in pot and pan washing systems as it will eventually draw the wares toward the intake-end of the wash sink (a phenomenon called “pan migration”) where they can potentially “pile up”, blocking the inlet manifold and starving the pump by restricting the fluid flow to the inlet. This occurs on all existing pot and pan washing systems, including systems utilizing linear intake manifold 130 shown in FIG. 2, which includes holes evenly spaced across the entire surface of the intake manifold. In the case of intake manifold 130 the even spacing of holes result in over 90% of the fluid transfer from the sink to pump 150 takes place in the first 50% of the intake, creating a large vacuum due to the suction of the water through holes in the intake. In addition, the fluid entering pump 150 is fairly turbulent as the path of most of the fluid must turn a sharp angle (generally ninety degrees) almost immediately from the point in which the fluid enters intake manifold 130 to the point in which the fluid enters pump 150. This too reducing the efficiency and performance of pump 150.
In order to provide the most efficient wash action within the entire volume of the wash sink it is desirable to develop a pump intake manifold that will introduce fluid to the pump inlet in such a way as to minimize the vacuum effect of the pump (as it draws in the fluid) and to minimize the turbulence of the fluid prior to reaching the pump inlet.
Although a machine that employs a wash tank and jet stream of the type described above is extremely useful for washing pots and pans, it is less desirable for washing smaller items such as utensils. In addition, it is difficult to separate items that require different levels of cleansing within the single wash tank of the above-described washing machine. In an attempt to provide a segregated wash area for items such as utensils, utensil baskets are often located within the wash tank. The invention disclosed in U.S. application Ser. No. 09/947,485 provides a powered utensil basket that captures a jet stream from the washing machine in which the basket is located to maintain the washing action of the machine within the basket. Although the powered utensil basket does provide a segregated washing area for utensils and other items that is removable from the washing machine, the basket itself is rather bulky and often not utilized in operation. Therefore, it is desirable to provide a segregated washing area within a wash tank that does not require the placement of a bulky utensil basket in the wash tank, while at the same time maintaining the wash action of the machine.